In a variety of applications of optical fiber lasers emitting light in the form of pulses (pulsed optical fiber lasers), it is often required to randomly-modulate pulse trains (burst-mode). It is difficult to implement such a burst-mode when a high-energy optical fiber amplifier is employed in a pulsed optical fiber laser for obtaining high output energy, because the amplifier may be damaged due to overamplification.
As a reference related to a burst-mode laser, Korean Patent Laid-Open publication No. 2012-0122102 discloses a pulse laser device that includes a laser source outputting an optical pulse and a laser source for outputting a continuous light and controls the duration of the continuous light to thereby maintain the profile of optical pulse trains coherently, and a method for controlling the device.
In the state-of-the-art, as an approach for implementing a burst-mode in an optical fiber laser, an optical modulator is disposed at the end output stage for preventing damage to an optical fiber amplifier and ensuring stability of a laser system.
Unfortunately, the approach requires employing expensive additional devices for driving the optical modulator, and thus the system becomes complicated and expensive. Moreover, the approach harms flexible operation requirements and high durability of an optical fiber laser, and consumes much power for driving the optical modulator.